A Brief Discussion on the Working Principle of aoi Optical Inspection Instruments to Reduce Labor Costs

A Brief Discussion on the Working Principle of aoi Optical Inspection Instruments to Reduce Labor Costs

A Brief Discussion on the Working Principle of aoi Optical Inspection Instruments to Reduce Labor Costs
To effectively control the quality of smt soldering and reduce labor costs, it is necessary to make good use of the automated aoi optical inspection instrument. To use the automated aoi optical inspection instrument well, one must understand its working principle. Only in this way can one know the reasons behind it when dealing with actual defect detection. aoi inspection equipment is a branch of artificial intelligence automation, and its principle is to imitate the process of manual inspection of smt soldering quality. By using artificial light sources instead of natural light and optical lenses instead of human eyes, images of components or solder joints are obtained through optical lens photography. Then, after processing and analysis by a computer, the defects and faults of soldering are compared and judged by imitating the human brain. But machines are machines. Under the current circumstances, they cannot be as flexible and adaptable as humans. This is why we need to understand the working principle of the automated aoi optical inspection instrument: by mastering the aoi principle, we can better play the role of aoi quality inspection. This will enhance product quality and reduce labor costs. ​
A Brief Discussion on the Working Principle of aoi Optical Inspection Instruments to Reduce Labor Costs
The general process of aoi inspection is the same, mostly through graphic recognition methods. The standard digital images stored in the AOI system are compared with the actual detected images to obtain the detection results. For instance, when inspecting a certain solder joint, a standard digital image is established based on a complete solder joint and compared with the actual measured image. Whether the inspection result is passed or not depends on the standard image, resolution and the inspection program used. Various algorithms are used in graphic recognition, such as calculating the ratio of black to white, color, composition, averaging, summation, difference, plane, and corner. ​
The light irradiation of aoi inspection equipment can be divided into two types: white light and colored light. White light uses 256 levels of gray scale, while colored light uses red, green, and blue light. When the light shines on the surface of the solder/components, it is then reflected into the lens, generating a three-dimensional display of a two-dimensional image to reflect the height and color difference of the solder joints/components. People judge and recognize objects based on the amount of light reflected back. A large amount of reflected light indicates brightness, while a small amount indicates darkness. AOI works on the same principle as human judgment. ​
aoi inspection equipment can be classified into single-lens and multi-lens types in terms of the number of lenses. This is merely one option for the implementation of technical solutions. It is hard to say which method is definitely better, as a single lens can also obtain excellent inspection images when illuminated from different angles by multiple light sources. Especially for the relatively rough surface of lead-free welding, which can produce weld points of different shapes, easily form bubbles, and have the characteristics of one end of the part lifting up, the new aoi inspection equipment has also undergone adaptive hardware and algorithm updates. ​